Musitronics - Mutron Phasor II

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
analogguru
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Post by analogguru »

Here they are:

Mutron Phasor II guts (with schematic)

enjoy,
analogguru
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Musitronics - Mutron Phasor II
Musitronics - Mutron Phasor II
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Post by Bernardduur »

Someone has a readable schematic? :)
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analogguru
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Post by analogguru »

with component values ?

Only have the schematic and guts from above. from both together it should be possible to make a schematic. but don´t have the time to do it now.

It´s a 6-stage-LDR-phaser

analogguru
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Post by RLBJR65 »

The Input and filter section look like they are the same as BI-Phase.

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Post by RLBJR65 »

I figured I could redraw the schematic much quicker than I will be able to trace it. Listed what ever I could make out from the original. Parts in red are questionable anything left unmarked I don't have a clue.

Anyone who wants to jump in please feel free to fill in the blanks or correct anything I got wrong :wink:

Edit: removed old links added new ones.
https://img141.imageshack.us/img141/3586 ... pg1qd6.gif
https://img141.imageshack.us/img141/1368 ... pg2wb4.gif
Last edited by RLBJR65 on 02 Feb 2008, 13:05, edited 1 time in total.

Bernardduur
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Post by Bernardduur »

Thanks man! You have great eyes :)

The first cap is 33 pF
rate potmeter is 25k log
I can't read the rest
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Post by reb »

I have one of these. I'll crack it open tonight

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RLBJR65
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Post by RLBJR65 »

Thanks Bernardduur a little photo editing and some of it popped right up.
Also having the Bi Phase schematic helped :wink:

Not the best at tracing but I think its almost done!

Reb if you open yours up can you check / verify a couple of things?
I marked some stuff in this pic http://i18.tinypic.com/866mxe0.jpg
Actually if you could, PLEASE check ALL the ceramic and greenie cap values just to be sure.

Ooops just noticed I marked a couple of the questionable diodes in the PS as 1N4247A should be 1N4742A (9.1V Zener) or maybe 1N4743A (9.9V zener)

Edit: removed old links added new ones.
https://img141.imageshack.us/img141/3586 ... pg1qd6.gif
https://img141.imageshack.us/img141/1368 ... pg2wb4.gif
Last edited by RLBJR65 on 02 Feb 2008, 13:05, edited 1 time in total.

analogguru
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Post by analogguru »

Transistor in the + power supply should be 2SC 828 instead of 829
Zener diodes are 1N 4742A = 12V/1W zener-diode

the 8k2 resistor in the feedback path near the input will probably be a 6k2.

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Post by RLBJR65 »

Thanks analogguru.
My eyes must have been getting fuzzy when I looked at the diode data sheet :lol:

8K2 is correct, I'm past that part tracing the board.

PS is done !

Signal path almost done between what I have traced and what I see on the schem / pics. I'm down to the cap in parallel with 8K2 in the feed back of the output.

Oscillator is the biggest Q since half is not visible on the trace side.

I’ll post schematic revisions as soon as I can.

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Post by reb »

Took a look last night.

The board in mine is different. I need a MM which measures caps, which I'll grab on a rat shack run today.

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Post by RLBJR65 »

Okay here is as far as I've gotten.

https://img140.imageshack.us/img140/4820 ... pq2sy3.jpg

Any way you can post some pics Reb?
No need to measure the caps, codes would be fine.

Edit: removed old links added new ones.
https://img141.imageshack.us/img141/3586 ... pg1qd6.gif
https://img141.imageshack.us/img141/1368 ... pg2wb4.gif
Last edited by RLBJR65 on 02 Feb 2008, 13:06, edited 1 time in total.

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Post by reb »

D'oh! the small ceramic one in by the IC fell into pieces when I took out the board. ;-( it's in pieces where the value is marked. If I look close, I think it the last 2 characters are 0k, but no luck as to what's before it.

heres's some pics. The camera is pretty good, I just don't have much exp taking these types of photos.

Image
Image
Image
Image

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Post by RLBJR65 »

Thanks Reb!
Your board is the same just has some different component types.
Common practice of many builders was to use whatever components were available or cheapest ( maybe reverse that :lol: ) when they needed them.

It looks like the 1uF cap has been removed from yours. I can't tell from the trace side pic if it was jumpered. It would have to be for the effect to work though.

Somebody suggested offline that the missing cap value is 820pF.
It looks like 820pF on original schem to me now :wink:

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Post by reb »

I have the 1uF cap. it fell out when I opened the box!
I'll look at my pieces again to see if I see 820pF???!!
I guess I'll throw one in & see if it works.

thanks

super velcroboy

Post by super velcroboy »

analogguru wrote:Here they are:

Mutron Phasor II guts (with schematic)

enjoy,
analogguru
that is a great website!

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Post by RLBJR65 »

Reb was that a working pedal?
Might as well replace all of the Electrolytic caps while you have it open.

Could you take off that piece of metal under the jacks and take another pic of the trace side? That way I can trace the oscillator circuit and this will be done :D

Thanks
Richard

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Post by reb »

mine worked fine before I opened it. I'll see about removing the metal plate tomorrow night & take some photos before I lock it back up. I'll probably put a new switch in & wire for true bypass.

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Post by Redhouse »

The two diodes up by the red switch are kinda fried looking too.

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Post by RLBJR65 »

Thanks Reb :D I really appreciate the help! The pics you posted already helped out a lot since I was able to verify most of the cap values from them.
Redhouse wrote:The two diodes up by the red switch are kinda fried looking too.
I was going to mention that too then I thought it kind of looks like its some crusty old crud that came in from around the switch opening. It’s defiantly worth checking them out while it’s open.

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